When rendering fire and smoke the camera will not render the smoke/fire effect, but the viewport will
I can’t believe nobody answered you more quickly.

Cycles doesn’t support smoke/fire with GPU. You can only use CPU. I know, what a bummer. I tried to do a tutorial the other day and it takes hours to render one frame with my 8 thread system…too slow and I can’t afford to by a 28 thread processor. I also tried render farms which are quick and work but one 10 second animation in 2k would have cost $16.

Of course once its in HD you see all sorts of stuff you don’t like so you’ll end up rendering it 5x to get what you want so that would have been $80. Not bad if you have a paying gig, you can factor it into the overall cost of the project.

If you are like me and just dipping your toe into the water, you’ll have to be patient and wait for the blender devs to create GPU support. If you have a real project that pays you can buy hardware (lots of CPU’s) or pay a render farm.

Good Luck.